There has been known a motor control device that detects or estimates a temperature of a motor or a power converter and limits a current command value in accordance with the temperature, so as to prevent breakdown of a switching element of the power converter that supplies power to the motor, an element of a control circuit, and the like, due to heat generated by an excess current. For example, a device disclosed in Patent Literature 1 estimates an increased temperature of a motor based on a current flowing in the motor. Further, during halting of current supply to the motor, the device estimates a decreased temperature of the motor from a heat radiation coefficient of the motor.
There is known a technique where a temperature of an evaluation place, which is correlated with a detected temperature of a temperature detector installed in one place on a substrate, is estimated based on the detected temperature. According to this known technique, when current supply is to be restarted after being halted, there is assumed a method in which a decreased temperature of the evaluation place during the halting period is estimated from a decreased temperature of the detection place during the halting period. Further, there is assumed a method in which an estimated temperature of the evaluation place during the halting is previously stored, and a temperature of the evaluation place at the time of the restart is estimated by the prior art of Patent Literature 1 based on a decreased temperature during the halting and an increased temperature estimated from a current at the time of the restart.
However, when an ambient temperature changes during the halting period of the current supply, the detected temperature of the temperature detector is affected by the change, making it impossible to correctly estimate the decreased temperature of the evaluation place. This as a result makes it impossible to correctly estimate the estimated temperature of the evaluation place at the time of the restart.
Patent Literature 1: JP 2892899